Roof-supporting assembly for hydraulic roof-supporting system

ABSTRACT

This invention relates to a roof-supporting assembly for a hydraulic roof-supporting system for longwall faces, which roofsupporting assembly comprises three frames placed side by side of which either the two outer frames jointly or the frame in the middle can be advanced and wherein the frames are coupled by paired control cylinders operable in contrary directions for correcting the relative positions of the frames, the annular piston face in one of each pair of cylinders having the same effective cross-sectional area as the full piston face in the other cylinder and the chamber on the full piston face side in one control cylinder being connected to the chamber on the annular piston face side in the other cylinder for keeping the frames parallel.

United States Patent [72] Inventor Friedrich-Alexander BrosowskiCastrop-Rauxel, Germany [21] Appl. No. 820,808

[22} Filed May 1,1969

[45] Patented July 13, 1971 i 73] Assignee Klockner-Vi'erke AG.Duisburg, Germany [32] Priority July 1, 1968 [33] Germany [54]ROOF-SUPPORTING ASSEMBLY FOR HYDRAULIC ROOF-SUPPORTING SYSTEM 3 Claims,4 Drawing Figs.

[52] U.S.Cl 61/45, 248/357 [51] lnt.Cl E2ld 15/44 [50] Field of Search 61 /45.2; 348/357; 299/31, 33

[56] References Cited UNlTED STATES PATENTS 3,505,823 4/1970 Bell 61/45D 3,120,105 2/1964 Kibble etal 61/45 FOREIGN PATENTS 766,537 1/1957Great Britain 1. 61/45 874,435 8/1961 Great Britain 61/45 1,028,5164/1958 Germany 61/45 1,169,399 5/1964 Germany 61/45 Primary Examiner-Dennis L. Taylor Attorney-Malcolm W. Fraser ABSTRACT: This inventionrelates to a roof-supporting assembly for a hydraulic roof-supportingsystem for longwall faces, which roof-supporting assembly comprisesthree frames placed side by side of which either the two outer framesjointly or the frame in the middle can be advanced and wherein theframes are coupled by paired control cylinders operable in contrarydirections for correcting the relative positions of the frames, theannular piston face in one of each pair of cylinders having the sameeffective cross-sectional area as the full piston face in the othercylinder and the chamber on the full piston face side in one controlcylinder being connected to the chamber on the annular piston face sidein the other cylinder for keeping the frames parallel.

PATEr-HFHJuumn 3,592,011

sum 2 m 2 INVENTOR ROOF-SUPPORTING ASSEMBLYFOR HYDRAULIC ROOF-SUPPORTINGSYSTEM SUMMARY OF THE INVENTION I This arrangement permits the frames tobe kept parallel even when they are advanced on a rise or dip facebecause the direction of the advancing frames is continuously correctedby virtue of the pistons in the control cylinders being displacedthrough like distances. Special control means. for ensuring paralleladvance of the frames are not therefore needed. The realignment of theframes need not take place until the advancing movement has beencompleted. For this purpose the hydraulic fluid is admitted into thecontrol cylinders by programmed control means.

This has the advantage of simplifying control and of improving thesafety of roof control since during self-advance of the roof-supportingassemblies the miner can keep his eye on the roof which he was unable todo in the past because his attention was concentrated on controlling thecontrol cylinders.

When the advancing steps are long and the frames are placed in closejuxtaposition, the disposition and accommodation of the controlcylinders in the assemblies presents some difficulty. In suchcircumstances the fully extended length of the piston rods of thecontrol cylinders is often insufficient to provide the desired length ofeach advancing step.

By subdividing the control cylinders the invention permits the availablelength of advance of the frames to be increased without at the same timein any way impairing the functional reliability of the controlcylinders.

According to the invention this is achieved in that each controlcylinder comprises two parallel single cylinders which are located sideby side and firmly interconnected, and which contain pistons to whichpressure is simultaneously applied urging said pistons in contrarydirections, the piston rod of each piston being linked to one of theneighboring frames and being guided so that it cannot rotate in itscylinder.

This permits the advancing step to be considerably lengthened beyondthat which single cylinders would permit. On the other hand, eachindividual cylinder need be attached to only one of the neighboringframes because the cylinders themselves cannot rotate.

Where hitherto two hydraulic frames were connected by two advancing ramcylinders in which pressure was simultaneously applied to the twopistons in contrary directions so that the piston moved in oppositedirections, piston rods had to be used which extended through the lengthof the cylinder. Otherwise difficulties could have arisen because of theability of the pistons to rotate in the cylinders. In the arrangementaccording to the invention the necessity of providing throughtype pistonrods is avoided.

In practice rotation of the pistons in the cylinders is prevented byproviding one piston rod of the two single cylin ders forming a controlcylinder with a parallel guide rod which is firmly attached to saidpiston rod and slidably movable in guide means on one of the singlecylinders.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a plan of a roof-supportingsystem according to the invention prior to the center frame beingadvanced,

FIG. 2 is a view similar to FIG. 1 showing the system after the centerframes has been advanced,

FIG. 3 is a perspective fragmentary view of three props of framesforming an assembly, showing the division of the control cylinders intopairs, and

FIG. 4 is a part sectional side elevational view, on an enlarged scale,of a control cylinder of the system according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION I trolling the roofat a longwall working face by placing assemblies of the illustratedkindside by side along the length of the face. Each assembly comprises threeparallel frames A, B and C. In the illustrated embodiment each frameconsists of a roofbar 1, two hydraulic props 2 which align in thedirection of the roofbar and a soleplate3. The three frames are ofcompletely identical construction.

Double-acting ram cylinders 6 and 7 for advancing the frames areinterposed between each two neighboring frames. By appropriatelyadmitting hydraulic fluid into these ram cylinders the center frame Bcan be advanced while the two outer frames A and C remain tight. Ifhydraulic fluid is admitted into the ram cylinders 6 and 7 in theoppositely acting direction the two outer frames A and C can be advancedwhile the center frame B remains tight.

The props 2 of the outer frame A are linked to the corresponding props 2of the center frame B by control cylinders 11 and 12. The props 2 of theouter frame C are linked to the corresponding props 2 of the centerframe B by control cylinders l4 and 15.

The cylinders 11 and 14 as well as the cylinders 12 and 15 form pairsand they are operated in contrary directions for correcting the relativepositions of the frames. The cylinders of each pair differ slightly insize.

In actual fact the annular piston face in the cylinder 11 has exactlythe same effective cross-sectional area as the full piston face in thecorresponding cylinder 14, and the same applies to the two other controlcylinders 12 and 15, which are attached to the rear ends of the frames.For keeping the frames in relative parallelism the working chambers onthe full piston face sides in the cylinders 14 and 15 are connected tothe chambers on the annular piston face sides in the two controlcylinders 11 and 12. Hence, the piston displacements in the pairedcontrol cylinders are always equal. If during a change in direction forinstance the soleplate of the center frame B should be pulled out ofalignment, the props 2 of the center frame B will be tilted. However, atthe end of the advance of this frame the contradirectional admission ofhydraulic fluid into the above-defined chambers in the paired controlcylinders operates to correct the positions of the props and of theframe.

FIGS. 3 and 4 show a pair of control cylinders 11 and 14 in greaterdetail. From these figures it is seen that each of the control cylindersis actually formed by two single cylinders 40 and 41. Since all thecontrol cylinders are of identical construction only the construction ofthe control cylinder 14 need be described in detail.

The two single cylinders 40 and 41 are placed parallel side by side.They may be firmly interconnected in any convenient way, the connectionbeing shown as a weld 42 in the embodiment illustrated. The pistons inthe single cylinders 40 and 41 of which one is shown in FIG. 4 at 43move in opposite directions. Hence, pressure is applied to the pistonface 44 and at the same time pressure is also applied to the face of thepiston that cannot be seen inside the single cylinder 40. In otherwords, the hydraulic pressure in the two cylinders acts in contrarydirections. Consequently, when the piston rods 45 and 46 of the twosingle cylinders 40 and 41 forming the control cylinder 14 are fullyextended, the overall length of the control cylinder will be three timesthe maximum stroke of one of the pistons and this length will contractto the length of the piston stroke when the piston rods are fullyretracted.

The ends of the piston rods 45 and 46 are provided with transverse bores48 and 49 which are adapted to receive pivot pins 50 which in turn arereceived in fork-shaped members 51 formed on the shackles 13.

The bores 4% and 49 are provided in transverse head members 53 and S4.The head member 54 on the piston rod 46 of the single cylinder 41carries a lateral arm 53 to which a guide rod 56 extending parallel tothe piston rod 46 and the cylinder 41 is attached. This guide rod isadapted to slide in a sleeveshaped guide 57 secured to the body of thecylinder 41.

This arrangement prevents the piston rods 45 and 46 and their associatedpistons from rotating inside their cylinders 40 and 41.

What I claim is:

1. A roof-supporting assembly for a hydraulic roof-supporting system,which roof-supporting assembly comprises three frames placed side byside of which either the two outer frames jointly or the frame in themiddle can be advanced and wherein the frames are coupled by pairedcontrol cylinders operable in contrary directions for correcting therelative positions of the frames, the chamber on the full piston faceside in one control cylinder being connected to the chamber on theannular piston face side in the other cylinder for keeping the framesparallel, characterized in that each control cylinder comprises twoparallel single cylinders which are located side by side means rigidlyconnecting said cylinders, and pistons in said cylinders to whichpressure is simultaneously applied urging said pistons in contrarydirections, means to link the piston rod of each piston to one of theneighboring frames, and means to guide each piston so that it cannotrotate in its cylinder.

2. A roof-supporting assembly according to claim 1, in which the ends ofthe piston rods are provided with pivot pins receivable in recesses inshackles connected to the frame.

3. A roof-supporting assembly according to claim 1, comprising a headmember on the outer end of each piston rod, each head member having atransverse bore, a pivot pin in each bore, shackles connected to theframes and fork-shaped members on said shackles to receive said pivotpins respectively.

1. A roof-supporting assembly for a hydraulic roof-supporting system,which roof-supporting assembly comprises three frames placed side byside of which either the two outer frames jointly or the frame in themiddle can be advanced and wherein the frames are coupled by pairedcontrol cylinders operable in contrary directions for correcting therelative positions of the frames, the chamber on the full piston faceside in one control cylinder being connected to the chamber on theannular piston face side in the other cylinder for keeping the framesparallel, characterized in that each control cylinder comprises twoparallel single cylinders which are located side by side means rigidlyconnecting said cylinders, and pistons in said cylinders to whichpressure is simultaneously applied urging said pistons in contrarydirections, means to link the piston rod of each piston to one of theneighboring frames, and means to guide each piston so that it cannotrotate in its cylinder.
 2. A roof-supporting assembly according to claim1, in which the ends of the piston rods are provided with pivot pinsreceivable in recesses in shackles connected to the frame.
 3. Aroof-supporting assembly according to claim 1, comprising a head memberon the outer end of each piston rod, each head member having atransverse bore, a pivot pin in each bore, shackles connected to theframes and fork-shaped members on said shackles to receive said pivotpins respectively.